CX has 10 YYZ-HKG flights per week for a while and AC does not seem to have any interest of increasing its daily frequency, or introduce a practical alternative via YVR as a 2nd choice by levering on AC7/8.

MU began thrice weekly YYZ-PVG service a short while ago and is selling discount J to HKG for about $2,000 cheaper than AC, but requiring a transit connection at PVG. No visa is required for Canadian nationals.

Rumours are that CZ will also begin CAN-YYZ service soon. It currently code-shares with WS on the YYZ-YVR segment.

What surprised me is PR. Their fares to Asia appear to be in line with CX and AC. Why would someone want to fly them for the same price as CX and AC? PR does not belong to any alliance.